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Step-by-step Guide to Resolve PostgreSQL Collation Mismatch

1. Backup the "gvmd" database
   Ensure you're in a directory with write permissions for the postgres user, like /tmp:
   cd /tmp

Attempt to backup the "gvmd" database:
pg_dump gvmd > gvmd_backup.sql

If you encounter a collation version mismatch warning, you can proceed. This warning is expected given your situation.

2. Refresh the collation for template1 database
   As many operations depend on template1, ensure it has the right collation version:
   psql -c "UPDATE pg_database SET datallowconn = TRUE WHERE datname = 'template1';"
   psql -d template1 -c "ALTER DATABASE template1 REFRESH COLLATION VERSION;"

3. Refresh the collation for postgres database
   psql -d postgres -c "ALTER DATABASE postgres REFRESH COLLATION VERSION;"

4. Create a new database
   Attempt to create a new database named "gvmd_new":
   createdb gvmd_new
   If you encounter a collation version mismatch error related to template1, ensure you've followed Step 2 correctly.

5. Refresh the collation for gvmd_new database
   psql -d gvmd_new -c "ALTER DATABASE gvmd_new REFRESH COLLATION VERSION;"

6. Dump and restore the "gvmd" database into "gvmd_new"
   pg_dump gvmd | psql gvmd_new

7. Terminate active connections to "gvmd"
   Before dropping the original "gvmd" database, ensure no active connections are using it:
   psql -d postgres -c "SELECT pg_terminate_backend(pg_stat_activity.pid) FROM pg_stat_activity WHERE pg_stat_activity.datname = 'gvmd' AND pid <> pg_backend_pid();"

8. Drop the "gvmd" database
   dropdb gvmd
   If you encounter an error indicating active connections, ensure you've followed Step 7 correctly.

9. Rename "gvmd_new" to "gvmd"
   createdb gvmd --template=gvmd_new

10. Cleanup (Optional)
    If everything is working as expected with the new "gvmd" database:
    dropdb gvmd_new